Abrasive article



5&1-2481filed h ar. 4, 1922,-and associated" Patented Apr. 20, 1926.

UNITED STATES FRANCIS GURNEY OKIE. OF ST. PAUL, MINNESOTA, ASSIGNOR TOMINNESOTA MINING PATENT .oiirlca.

AND MANUFACTURING COMPANY, on ST. PAUL, MINNESOTA, A oonrbfl'rroN orMINNESOTA,

ABRASIVE ARTICLE.

Ne Drawing. Original application filed March 4, 1922, Serial No:541,248. Dividedand till filed December 29, 1923.- Serifll No. 683,522.

sheet form, and more particularly the treat-,4

ment of material for the-purpose of forming or attaining compositestructures, of which well known forms of abrasives such as what iscommonly known as sand-paper is an. example. The present application is,in part, a continuation of my copending application, Serial No. 428,289filedDecJ4, 1920', ahd a division of m 1 application, Serial No.

with my. applications, 7 Serial Nos. 488,287 filed Dec. 24, 1920 and670,542 filed Oct, 2%, 1923. i I f Although I hereinafter disclose thepractice of my invention in 1 connection with abrasives such assand-paper itwill be understood that my invention, or certain featuresthereof, have a wider-field of utility.

Composite structures of theabrasive type such as sand-paper or emerycloth comprise generally (a) a base of sheet material, which may befelted as in the [case of paper or woven as in the case of cloth, (b) amore or less finely c'omminuted resistant material having abradingproperties, such as garnet or corundum, and (c) a binder generally inthe form of a glue which serves to bind the abrasive to the base.

T he abrasive products as produced at present have as incidents certainfeatures among which are affinity for. moisture rendering themsubstantially inutile in the presence of water or moisture. andcracking, with consequent exposure of the base, when bent I Theprincipal objects of my present invention are the provision. of a binderwhichfunction more efliciently than any known to me, the provision of anabrasive articlehav ing a binder eharacterizedjb'y, fle'xibilit withoutcracking or other undesirable e fects; the provisionof such anarticlechar acterized by extensibility and compressibili tyto..accommodate'itself to flexion of the.

base; tli'eproyi'sion of such an article having a bindei by meansofwwhichlthedesired adhesive action between it and the base is attainednot only. efliciently but also with a desirable degree of acceleration,and more particularly the provision of such an article having a binderinwhich the drying action will be efiective from the contact surfacebetwee'nit and the base outwardly; the provision'of such an articlehaving a binder in which the -drying action will be efiective from theouter surface inwardly; the provision therein of a bindercharacterizedby a. drying; action that permits of handling the pro uctwith a minimum of delay and moreparticularly such handling without im-"0 pairment of the superficies ofthe material; the provislon therein ofa binder characterized by an accelerated drying action; the

provision therein of a' binder characterized by a limitation of itsdrying action; the pro-. vision of an improved moisture-proof materialand. especially material in a sheet form, and more particularly onehaving means for causing a moisture-proofing 'agentto penetrate into thematerial; the provision of a moisture-proof composite abrasivestructure; the provision of a binder having moisture-proofing functlons,and the provision generally of an improved composite abrasive structureand of a method of producin'g the same, together with such other objectsand additional benefits and advan-- tages as may hereinafter appear orbe pointed out In the employment of my present in- I yention for theproduction of sand-paper and the like. suitable for employment in awater abrading operation (which I cite for purposes of example) I use asthe base a sheet of material (which may be paper) V of the bindermaterial.

as will conveniently serve the employment contemplated, and as theabrasive such comminuted material (which may be crushed garnet)similarly adapted to serve the function in view.

-.It is desirable that the binder utilized.-

haye the functions and characteristics not only of great mechanicalstrength and of great binding strength, but also that it benon-hygroscopic, permeative, moisture resistant, easily worked, readilyobtainable, inexpensive and facilely applied. V

I have discovered that gums of such types as rosin are peculiarlyadapted for the 'attainment of these ends, and ordinary turpentine rosinis preferred by me as best attaining the desired end, viewed fromcertain aspects. Other gumsand resins, natural or synthetic,havmg thedesired characteristics may also be utilized.

In preparing the binder for use, the

is used 1n connection with a. suitable. vehicle which I prefer is of atype such as linseed oil, China-wood oil, otherwise known as tung oil,perilla oil or fish oil, or even a semi-drying 011 such as soya-beanoil, for

reasons which I" will proceed to explain.

In applying a gum prepared with a ve'- hicle such as China-woodoil toone surface of a base of paper, for example I have found that the actionof the vehicle involves a penetration of the base by'the vehicle,'f.or

example, China-wood oil or any similar drym 011 or semi-drying oil.

This results in a moisture-proofing of the material even against theabsorption of moisture through the surface opposite to that to which thebinder is applied, without at the same time defacing or otherwise'unvdesirably affecting such-opposite surface.

The penetration by the vehicle, particularly when coupled with the useof the char'fl actor of gum pointed out above, carries with it in suchpenetration a certain amount offinely divided gum so that a coating andbinding action is secured between the fibres v of elemental portions ofthe base which thus substantially'retards. if it does not entirelyprevent, disintegration of the material of the base, in addition topreventing access of moisture through the-baseto the plane 'of contactbetween the base and the main mass The eflicient action of the bindermaybe enhanced in the manufacture of sand-paper if the binder is appliedto the base by the use of pressure and the more or less finelydividedabrasive is then applied in such a manner as to cause it to adhere tothebinder.

" In order to accelerate the adhesion be-w tween the binder and thebase. I have dis covercd it desirable to use with the binder amodifyingagent the action of which is to cause a desiccation of the binderinitiated Due to the relatively .slow drying of bindersenerally,difiiculties are encountered in hand the structure, within aconvenient pe'ri because of the soft and sticky character-particularlyof the exposed surfaces of the binder. This objection I mitigate byassociating with'the improved binder a substance the action of-whichisto produce .an. accelerated drying action eflectlve pri- ,marily atthe exposed surface and working inwardly, andfor this 'urpose IIincorporate in the binder a m ifymg element peculiarly effective in itsactlon as an oxldlzmg agent onsuch vehicles as linseed, Chinawood ortung 011 and as a retarding agent with reference to the excessabsorption of the vehicle by the base.

The substance I have discovered to be particularly adapted for thispurpose is that well-known to the trade obtainable in the open marketand formed by a new electrolytic process white lead and which in myexperience is found .to be more satisfactory {hag any otherkuown form ofcarbonate of Whereas by itself the white lead adds but relatively littlestrength to -the binder, in, association in the binder with thebora-teof manganese it intensifies the action of the binder in holdingthe abrasive firinly' against the base.

For intensifying the-binding action of the binder and for intensifyingthe drying action of the dryers, and at the same time accomplishing suchendsby-the employment of a material which is eflicacious in holding themineral elements in suspension. without loss of siccative energy orreducing the relative vfluidity of the material, I have discovered thatit is advantageous to employ as part of the binder a paste dryer. Thismay to. form the paste dryer so as to have the minerals contalncdtherein in theform of acetate of lead and resmatc of manganese.

.I have found by experience that th paste dryer should be somewhat inthe nature of cheesy butter, rather softer, and of a light brownish greycolor. p

As'an auxiliary in (l) acccntuating the adhesion of the binder to thepaper, ('2) facilitating to a certain extent the spread :comprise suchmineral substances as sugar I ofvlead and borate of manganese suspendedin a resinous vehicle but I, find it preferable ilig of the binder, anddesired the consistency of the binder as is useful in. cases where it isdesired to render it more fluid, I have discovered that the use of ajapan dryer is desirable. dryer as that which is relatively free fromresin is convenient. One .form of this contains shellac, red lead,litharge,.manganese oxid, burnt umber, gum, linseed oil and tur- (3)modifying as pentine q. s.

In order body volulnetrlcally considered I prefer- I ably employ avarnish. consisting largely of that the siccative as castor oil or thelike,

China-wood oil, .linseed oil, perilla oil, or iish oil, boiled until itapproaches a solid state. As far as feasible this should be as free aspossible from glycerides and fatty acids. L

Though I have hereinabove disclosed certain forms of useful dryershaving various characteristics, and likewise intensifiers, I havediscovered that where it is advisable action thereof be limited, or atleast retarded, under certain conditions, or when producing material for'cer.- tain purposes, that it is desirable to incorporate in the bindera non-drying oil such Sand-paper madein accordance with the disclosureof my present invention is characterized by great fflexibility withoutany adverse effects, suchas cracking of hinder or base, or loosening ofone from the other.

The materialsused by me as hereinabove described may be varied incharacter so as hygroscopy,

to vary the characteristics of the binder from the standpoint ofadhesiveness, nonand flexibility. -Wher'e such variation in the use ofmaterials is employed to produce, for instance, increased adhesionbetween the binder and theabrasive, such increase may be attainedthough'possibly at a certain expense in its characteristic. of

flexibility. Due, however, to this very same increased adhesiveness, oneor more of the outer layers of the base may by the employment of a basewhich involves. the use of a built lip-structure having BBILUIIb" e re-,

ber of plies, certain of which may moved, or by shaving off partof thethickness of the base, or by splitting an ordinary sheet of paper. Thisis made possible. in the case of my improved binder since I am ableto'regulate the degree of its penetration of the paper, as" desired, andso, after soaking, I am able to split an ordinary sheet.

By this process I am enabled to obtain sand-paper characterized byextraordinary thinness and flexibility, to form sand-paper and the likewith a base so thin that such product ceuld not be manufactured. if thebase originally used were of the. thinness mummy-asses.

Such ato give the hinder the desired for such purposes.

the

opinion the ppt-imum, V a humidity being maintained in the drying ingtoo" crisp or brittle. A be removed as; y Y

noteworthy in that it not only: penetrates.

various oils,

fabric, and this without wea in that I am able' In my preferred practicewith Chinawood oil and rosin, the adhesive applied is of approximatelythe following proportions by weight and percentages v 7 Per cent.China-wood oil (tung oil) 106 lbs. 53 Hardened rosin j 24 lbs. 12Linseed oil 20lbs. 10 Dryer 2 lbs; 1 Thiuner ;say 18 lbs. 24

One of the virtues of a waterproof binder of. the present composition isthat it not only penetrates the supporting base, rendering itwaterproof, but also is of great utility as contrasted with organic glue(prepare from gelatinous matter) inasmuch as it may be used with oiledor waxed paper whichtreatment with binder to facilitate its applicationto the back, but also to increase its powers of penetration of the base,it maybe used cold. After the adhesive andv abrasive materials areapplied, the paper is, suitably force dried (or partially baked as it issaid), to the desired extent. by subjecting it in the usual manner to atemperature which I prefer to. control between 130 depending upon thedegree sired, an average of say a suitable degree of of hardnessdechamber to prevent the paper from becom- Th'e binder of mypresentinvention is thepaper etc. ofthe backing or base, but

penetrates. mixes with,"or combines with greases'and waxes that arecommonly used as water-proofing agents for ening, breaking down, orother deleterious mechanical or chemical effects.

In cases where the surface: of the fabric is not suitable* for theapplication of a smooth coating of thebinder I have found filler to thebase' it convenient to apply a to facilitate such' application. This mayconsist of any one of the known fillers hav likehase.

mg a clayey, silicon. or v v v In cases where it IS desirable ornecesthou'gh in. some cases 140.F. being in my F. and 150- F.,

sary to employ. a sizing coat, that is, ail

ing coat, which liminary auxiliary or additional coat or one 'of aplurality of finishing coats, I find that a. Ihinned composition similarto that disclosed herein as forming the binder itself, is satisfactory.As an example of the sizalso may be employed as a moisture-proofbacking, I submit the following formula by weight:

I Treated rosin 0r resin 2700 China woo'd oil 13962 Mineral dryers 7 9Thinuers 12611 An alternative formula for the same purpose ma includethe following ingredients by Weig t:

Treated rosin or resin 2700 China-wood oil 8100 Mineral dryers 83Thinners 8850 Linseed oil 2125 Any one of the formulae above set forthmay be employed depending upon the results desired or the conditionsunder which the sizing coat isto be applied. The sizing pends the degreeof penetration, if any, of

the material of the sizing coat into the binder carrying the abrasive.For example, it the sizing coat is applied substantially immediatelyafter a preliminary setting of the abrasive carrying binder has taken,place, there will result a penetration of the abra sive carrying binderbythe sizing coat, or a homogenizing of the binder coatand the sizingcoat, but regardless of the length of time of set of the binder, whenthe sizing coatis applied it adheres very tenaciously to the binder.

Alternately, if a considerable time-inter- .val is permitted to elapsebet-ween the presetting of the binder and the application of the sizingcoat, and sufficient suitable solvents are included in the sizing coatcomposition a partial solving of the binder wlllfresult, and thus bringabout As an example of one of my practices, I apply the binder oradhesive coat and substantially immediately thereafter I apply theabrasive. About an hour after the adhesive coat and abrasive materialare applied the sheet enters the drying room and remains thereforapproximately forty-eight hours preferably in a temperature varying'from100 t0-150 degrees F., partially cooling during the night when the heatsupply is reduced or shut ofl. The paper or cloth abrasive sheet isthenremoved from the drying room and if it is convenient to apply the sizingcoat, this is done so immediately. If not convenient to size at thattime the abrasive sheets are left on the rolls until it is so convenientto apply the sizing coat.- The time which the abrasive sheet is left onthe roll is, generally speaking, immaterial, though Imay apply thesizing coat at a particular phase of the hardening of the abrasivecarrying binder in order to enhance adhesivenes's. Consequently, thesizing coat may be applied at a convenient time, which may be as long asa week ortwo after the adhesive and abrasive have been applied, or atother times, depending on circumstances.

'hen the sizing is supported, and a moisture-proofing layer is )plied tothe back of the sheet, if desire as for example, if'the paper has notpreviously been watcr-proofed. This backmg layer may beof the samecomposition asthat of the sizing layer applied to the abrasive. Thesizing for the abrasive side is then carried out, or. maybe done substantially simultaneously wlth the application of the backing sizing.After the sizing or sizings have been applied the sheet sive by thesizing coat or whether there is any actual penetration, may not alwaysbe a vital factor in the production of a satisfactory moisture-proofabrasive sheet, because, as I have pointed out above, the sizingadheresquite tenaciously to the binder and abrasive, and while penetration andconsequent homogenization of the binder with the sizing coat gives amore intimate joint, a purely surface junction between the binder 0 isto be applied, the sheet is unrolled fronrthe rack on which it and thesizing coat is all that is essential to the production of a satisfactoryarticle, for some purposes, if the sizing coat is emplo ed.

ith further reference to. the junction ob-' tained between the adhesiveand the "sizing coat, I might explain that as the sizing coat is warmwhen applied to the abrasive and binder, there is produced a softeningof the binder, pending upon the factors pointed out. p

The following formulae by weight comprise additional materials which Ifind suitable for my purposes, and result each in the roduction of ahighly moisture-proof, flex- 1ble and tenacious binder and sizing coatfor abrasive devices U-binder. Treated rosin or resin; 2700 Linseed oil-1. 1 044 China-wood oil 7584 Mineral dryers 135 Thinners 2040 (Raisingusually employed with O -biqwler. Treated-rosin or resin 2700 Linseedoil -1 104A China-wood oil 7 584 Mineral dryers -.i.. 135 Thinners .i22255 It will be observed that the formula designated C-sizing issimilar in all respects to the composition of the C binder with theexception'that an increased proportion of thinher is employed. p

The following formulae by weight have also been tried but I haveobtainedmarkedly less satisfactory results with their use, and not onlydo not consider them practicable but quite inferior:

D-bz'nder.

Venetian red or white lead Dissolved rubber Venice turpentine 900Treated rosin or resin (proportions-- shellac 000, copal 1800) 2700Linseed oil i716 Mineral dryers 90 D-sz'sing coat .us-ually employedwith D- binder.

Venetian red or white lead 900 Dissolved rubber 900 Venice turpentine l900 Treated rosin or resin (proportionsshellac 900, copal 1800) i 2700Thiuners 2000 Linseed oil- H16 Mineral dryers 90 I An alternative formof binder similar to that designated D-binder is as follows:

I tinder. Venetian red or white lead 1350 Venice: 'ientine 900 which mayresult in penetratlon, de-

the O and D binders, that the sizing coat 1s E sieving usually employedwith E-binder.

Venetian redcr white lead 1350 Venice turpentine 900 Gopal 2700Thinner-s 2000 Linseed oil r 6407 Mineral dryers 135 It will be observedhere, as in the case of ofsubstantially' the same materials as that ofthe binder or abrasive carrying coating, with the exception thatthinners are added, or if already present, increased sufficiently topermit the top sizing coatto flow readily between the grains of abrasiveand amalgamate with the binder or adhesive coat. lVithin my experience,all formulae containing both rubber and an oil are open; to graveobjections, in that these two substances areantipathetic, and under theaction of the oil, any abrasive containing rub-' ber known to me tendsto premature disintegration.

I have also employed as a sizing coat both natural and so-calledimitation or synthetic shellac cut in alcohol, and, alternately meltedorotherwise made fluid with oil and gum compositions, or so-calledtreated cellulose (cellulose nitrate, cellulose acetate,

- cellulose contagenate), or synthetic resins such as condensationproducts of so-called bakelite is a type.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent is:

1. The new article of manufacture in the nature of sandpaper comprisinga flexible sheet of fabric, a grit or layer of abrasive particles, awaterproof stable penetrative adhesive bond interposed between said gritand said sheet, and a compensatory auxiliary bonding coat applied to thearticle, said bond and auxiliary coat being of a nature to maintain thebonding effect throughout the effective abrading life of the abrasivearticle when employed in a water abrading' operation and notdeleteriously affecting the flexibility of said sheet when dry.

2. The new article of manufacture in the nature of sandpaper comprising'a flexible sheet of fabric, a grit or layer ofabrasive particles, awaterproof stable adhesive bond interposed between said grit and saidsheet, and. an auxiliary coat applied to the article, said bond andauxiliary coat cooperating-to prevent disin egration .of the sheet whenused in a water abrading operation, and being of a nature to maintainthe bonding effer-t throughout the effective abrading li-fe of theabrasive article when employed in a which the water abrading operationand not deleterisheet of fabric,

. effect throughout the effective and prevent disintegration of jarticlewhen operation.

6. The new article of manufacture in the not deleteriously affecting theexibility of dry said sheetwhen dry.

4. Thenew'article of manufacture in the nature of .sandpaper comprisingaflexible a grit or layer of abrasive particles, a waterproof stableadhesive bond interposed between said grit and said sheet, and anauxiliary coat applied to the article, said auxiliary coat being of acharacter to act as a solvent of and coalesce with said bond, and saidbond and auxiliary coat being of a nature to maintain the bonding effectthroughout the effective abrading life of the abrasive article whenemployed in a water abrading operation and not deleterioiilsly affectingthe flexibility of said sheet w e 5. Th e new article of manufacture inthe nature of sandpaper comprising a flexible sheet of tpaper ormaterial similarly. susceptible to uid penetration, a grit or layer ofabrasive particles, a waterproof stable adhesive bond interposed betweensaid grit and said sheet, said bond penetrating said sheet to protect itagainst water, an auxiliary coat of analogous character applied to thearticle and penetrating said bond, said auxiliar coat cooperating withsaid bond and the two being of a nature to maintain the bonding abradinglife the abrasive employed in a water abrading nature of sandpapercomprising a flexible sheet of aper or material similarly susceptible toaid penetration a grit or layer of abrasive particles, hesive bond inthe nature of a varnish, interosed between said grit and said sheet,said ondpenetrating said sheet' to protect it an auxiliary coat of thenature of a less viscous varnish, applied to-the article and penetratingsaid bond, said auxiliary coat and'bond being of a nature to maintainthe bonding efl'eet throughout the effective abrading life of theabrasive article when employed in water abrading operation.

7 The article of manufacture in the nature of sandpaper, comprising aflexible sheet of fabric, a grit or layer of abrasive particles, and aplurality of coats of waterproof material applied to said article, oneof said coats servin-g'as a stable waterproof coat applied to thearticle,

y grit and said sheet of a abrasive a waterproof stable ad adhesive bondinterposed between said grit and said sheet and of a nature to maintainthe bonding effect throughout the effective abrading life of theabrasive article when used in a water abrading operation, and another ofsaid coats serving as an auxiliary waterproofing agent which coacts withthe adhesive bond to prevent disintegration of the article when used insuch water abrading operation, and said coat not deleteriously affectingthe flexibility of the article when 8. The new article of manufacture inthe nature of sandpaper, comprising a flexible sheet of fabric, a gritor layer of abrasive particles, and a plurality of coats of waterproofmaterial applied to said article, one of said coats being applied to onesurface of the sheet and serving as a stable waterproof adhesive bondinterposed between said grit and said sheet and of a nature to maintainthe bonding effect throughout the effective -.a bradinglife of theabrasive article when sheet of waterproof fabric, a grit or layer ofabrasive particles,

and a waterproof stable adhesive bond interposed between said nature tomaintain the bonding effect throughout the effective abrading life ofthe abrasive articles when used'in a water abrading o eration and notdeleteriously affecting the exibility of said sheet when dry.

10. The new article of manufacture in the nature of sandpaper,comprising a flexible sheet of waterproof fabric,-a grit or layer ofarticles, and a waterproof stable adhesive 0nd interposed between saidrit and said sheet and an auxiliay coat applied to the article, saidbond and auxiliary coat cooperatin to prevent disintegration of theart1clei=,.and being of a nature to maintain thebondin effect thrgughoutthe effective abrading life of the abrasive article when used in a waterabrading operation and not deleteriously affecting the flexibility ofsaid sheet when dry.

11. The new article of manufacture in the nature of sandpaper,comprising a flexible sheet offabric one surface of which is treated toprevent disintegration when used in a water abrading operation, a gritor layer of abrasive particles, and a water'p'roofi stableadhesive bondinterposed between said grit and the opposite surface of said sheetwhich coacts with t e ad- I of a nature to maintain the bonding effectthroughout the effective abrading life of the abrasive article when usedin a water 'abrad ing operation and not deleteriously affecting theflexibility of said sheet when dry.

12. The new article of manufacture in the nature of sandpaper,comprising a flexible sheet of fabric one surface of which is treated toprevent disintegration when used in a water abrading operation, a gritor layer of abrasive particles, and a waterproof stable adhesive bondinterposed between said grit and the opposite surface of said sheet andan auxiliary coat applied to the article, said bond and auxiliary coatbeing of a nature to maintain the bonding effect throughout theeffective abrading life of ,the abrasive article when used in a waterabrading operation and not deleteriously affecting the flexibility ofsaid sheet when dry.

13. The new article of manufacture in the nature of sandpaper,comprising a flexible sheet of fabric, a grit or layer of abrasiveparticles, and a plurality of coats of waterproofing material applied tosaid article, one

of said coats serving as a rimary stable water-proof adhesive bondmterposed between said grit and said sheet and of a nature to maintainthe bonding eflect throughout the effective abrading life of theabrasive article, and another of said coats applied thereover serving asa secondary bond, and a third coat applied to the opposite surfaceserving as an auxiliary agent for preventing disintegration of thearticle and starving of the bond, said several coats not deleteriouslyaffecting the flexibility of the article when dry.

14. The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which includes applying to a flexiblesheet of fabric a grit or layer of. abrasive particles, and a pluralityof coats of waterproof material, by interposing as one of said coats astable water-proof penetrative adhesive bond between said grit and saidsheet the said adhesive bond being of a nature to maintain the bondingeffect throughout the effective abrading life of the abrasive article,allowing said adhesive bond to penetrate the sheet, and compensating forpenetration of said sheet by the bond by applying another of said coatsas an auxiliarybonding and waterproofing agent, and said coats notdeleteriously affecting the flexi bility of the article when dry.

15. The process of making a stable water= proof abrasive article in thenature of sandpaper or the like which'includes applying to a flexiblesheet of fabric a grit or layer of abrasive particles, and a pluralityof coats of waterproof material, interposing one of said coats as astable waterproof adhesive bond between said grit and one surface ofsaid sheet the said adhesive bond being of a nature to maintain thebonding effect throughout the effective abrading life of the abrasivearticle, and applying another of said coats to the opposite surface ofthe sheet to serve as an auxiliary agent, and allowing said latter coatto engage the sheet so as to cooperate with the' adhesive bond toprevent disintegration of the article when used in awater abradingoperation, and said coats not deleteriously affecting the flexibility ofthe article when dry. 1

16. The process of making a stable waterproof abrasive article in thenature of sanda paper or the like which includes employing a flexiblesheet of fabric which has been so f treated to prevent disintegrationwhen used to prevent disintegration when used in a water aib-radingoperation, applying thereto a grit or layer of abrasive particles, and awaterproof stable adhesive bond and an auxiliary coat, 'said bond andauxiliary coat cooperating with each other and being of a naturetomaintain the bonding effect throughout the effective abrading life ofthe abrasive article when used in a water-"abrading operation and notdeleteriously affecting the flexibility of said sheet when. dry.

18. The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which includes employing a flexiblesheet of fabric, one surface of which istreated to preventdisintegration when used in a water abrading o )eration, applying to theopposite surface thereof a grit or layer of abrasive particles, and awaterproof stable adhesive bond of a nature to maintain the bondingefl'ect throughout the effective abrading life of the abrasive articlewhen used in a water abrading operation and not deleteriously affectingthe flexibility of said sheet when dry, I

19. The process of making a stablewaterproof abrasive article in thenature of sandpaper or the like which includes employing a flexiblesheet of fabric one surface of which is ture to maintain thebonding'feifect throughout the. effective abrading life of the abra saidsheet when dry, and

sive article when used in a water abrading operation and not'deleteriouslv affecting the flexibility of said sheet when dry.

20. The process of making a stable waterproof axb-rasive article in thenature of sandpaper or the like which includes applying to a flexiblesheet of fabric a grit or layerof abrasive particles, and'a plurality ofcoats of waterproof material, interposing one of said coats as a primarywaterproof stable adhesive bond between said grit and said sheet and ofa nature to maintain the bonding effect throughout the effectiveabrading life of the abrasive article when used in a waterabradingoperation, applyin one of the other coats to the op osite si e of thefabric to serve as an auxiliary waterprpofing agent and applyin theother'of said coats over the interposed coat toserve' as a secondarybond.

21. The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which includes applying to a flexiblesheet "of fabric agrit or layer of abrasive particles, and a waterproofbond of a nature to maintain the bonding effect throughout the effectiveabrading-life of the abrasive article when employed in a water abradingoperation and not dele- .teriously affecting the flexibility of saidsheet when dry, and applyin a. waterproof auxilliary coat of analogous caracter to the artic e.

22. The of making a stable waterproof abrasive article in the nature ofsand-' paper or the like which includes applying to a flexible sheet offabric a grit or layer.

of abrasive particles, and interposing a waterproof bond of a nature tomaintain the bonding effect throughout the effective abrading life ofthe abrasive article when employed in a water abrading o ration and notdeleteriously aifectirw the exibility of uniting a waterproof auxiliarybonding coat of analogous character to the article.

23.- The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which includes applying to a flexiblesheet of fabric a grit or layer of abrasive particles, and interposin awaterproof bond of a nature to maintam the bonding effect throughout theeffective abrading life of the abrasive article when employed in a waterabrading operation and not deleteriously affecting the flexibility ofsaid sheet when dry, applying a waterproof auxiliary bonding coat ofanalogous character to the artic e, and applying heat after one of saidsteps.

24. The process of making a stable waterproof abrasive article inthenature of sand-' paper or the like which includes applying to --aflexible sheet of fabric a grit or layer of abrasive particles,-andinterposinga waterproof bond of a nature to maintain the bonding efi'ectthroughout the effective abrading life of the abrasive article whenemployed in a water abrading operation and not dcleteriously afl'ectinthe flexibility of said sheet when dry, an uniting a waterproofauxiliary bonding coat of analogous character to the article by theapplication of heat.

25. The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which includes applying to a flexiblesheet of fabric a grit or ayer of abrasive particles, and interposing awaterproof ,bond of a nature to maintain the bonding efi'ect throughoutthe effective abrading life. of the abrasive article when employed in awater abrading operation and not deleteriously afiectin the flexibilityof said sheet when dry, app ying a waterproof auxiliary bonding coat ofanalogous character to t e article, and applying heat after each of saidsteps.

26. The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which in'cludes a plying to a flexiblesheet of fabric, a grit or ayer of abrasive particles and inter ing awaterproof bond of a nature to maintain the bonding effect throughoutthe effective abrading life of the abrasive article when employed in awater abrading operation and not deleteriously affecting the flexibilityof said sheet when dry, which includes allowing the bond to penetratethe sheet,-and applying a waterproof auxiliary coat of analogouscharacter to the artic1e.--

27. The process of making a stable waterproof abrasive article in thenature of sandpaper or the like which includes applying to a flexiblesheet of fabricj -a grit or layer of abrasive particles and -interposinga waterproof bond of a nature to maintain the bonding effect throughoutthe effective abrading life of .the abrasive article when employed in a.water abrading operation and not deleteriously afiectin the flexibil1tyof said sheet when dry, whic includes allowing the bond to penetrate thesheet, applying a.

waterproof auxiliary coat of am 0 ous character to the article, andapplying eat afterone of said steps.

28. The process of making a stable waterproof abrasive article in thenature of sandpager or the like which includes applying to a exiblesheet of fabric, a grit or layer of abrasive particles and' interposinga waterproof bond of-a nature to'inaintain the bondeteriously affectingthe flexibility ofsaid sheet when dry, which includes allowing the.efl'ect throughout the effective abrading bond topenetrate the sheet,applying a waterproof auxiliary coat of analogous :haracter to thearticle, and applying heat tfter each of said steps.

29. The process of making a stable waterproof abrasive article in thenature of sandpaper, wl 'ch includes employing a flexible sheet offabric, treating said sheet to prevent disintegration when used in aWater abrading operation, applying thereto a grit or layer of abrasiveparticles, and interposing a waterproof stable adhesive bond of a natureto maintain the bonding effect throughout the effective abrading life ofthe abrasive article when used in a water ,abrading operation and notdeleteriously affecting the flexibility of said sheet when dry.

30. The process of making a stable waterproof abrasive article in thenature of sandpaper, which includes employing a flexible sheet offabric, treating one surface of said sheet to prevent disintegrationwhen used in a Water abrading operation, applying to the signed my name.

. FRANCIS GURNEY OKIE.

bond of a nature to

